// Copyright (c) 2016 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
//

package virtcontainers

import (
	"bufio"
	"context"
	"fmt"
	"os"
	"runtime"
	"strconv"
	"strings"

	"github.com/kata-containers/runtime/virtcontainers/device/config"
	"github.com/kata-containers/runtime/virtcontainers/store"
	"github.com/kata-containers/runtime/virtcontainers/types"
)

// HypervisorType describes an hypervisor type.
type HypervisorType string

type operation int

const (
	// FirecrackerHypervisor is the FC hypervisor.
	FirecrackerHypervisor HypervisorType = "firecracker"

	// QemuHypervisor is the QEMU hypervisor.
	QemuHypervisor HypervisorType = "qemu"

	// MockHypervisor is a mock hypervisor for testing purposes
	MockHypervisor HypervisorType = "mock"
)

const (
	procMemInfo = "/proc/meminfo"
	procCPUInfo = "/proc/cpuinfo"
)

const (
	defaultVCPUs = 1
	// 2 GiB
	defaultMemSzMiB = 2048

	defaultBridges = 1

	defaultBlockDriver = config.VirtioSCSI
)

// In some architectures the maximum number of vCPUs depends on the number of physical cores.
var defaultMaxQemuVCPUs = MaxQemuVCPUs()

// agnostic list of kernel root parameters for NVDIMM
var commonNvdimmKernelRootParams = []Param{ //nolint: unused, deadcode, varcheck
	{"root", "/dev/pmem0p1"},
	{"rootflags", "dax,data=ordered,errors=remount-ro ro"},
	{"rootfstype", "ext4"},
}

// agnostic list of kernel root parameters for virtio-blk
var commonVirtioblkKernelRootParams = []Param{ //nolint: unused, deadcode, varcheck
	{"root", "/dev/vda1"},
	{"rootflags", "data=ordered,errors=remount-ro ro"},
	{"rootfstype", "ext4"},
}

// deviceType describes a virtualized device type.
type deviceType int

const (
	// ImgDev is the image device type.
	imgDev deviceType = iota

	// FsDev is the filesystem device type.
	fsDev

	// NetDev is the network device type.
	netDev

	// BlockDev is the block device type.
	blockDev

	// SerialPortDev is the serial port device type.
	serialPortDev

	// vSockPCIDev is the vhost vsock PCI device type.
	vSockPCIDev

	// VFIODevice is VFIO device type
	vfioDev

	// vhostuserDev is a Vhost-user device type
	vhostuserDev

	// CPUDevice is CPU device type
	cpuDev

	// memoryDevice is memory device type
	memoryDev
)

type memoryDevice struct {
	slot   int
	sizeMB int
	addr   uint64
	probe  bool
}

// Set sets an hypervisor type based on the input string.
func (hType *HypervisorType) Set(value string) error {
	switch value {
	case "qemu":
		*hType = QemuHypervisor
		return nil
	case "firecracker":
		*hType = FirecrackerHypervisor
		return nil
	case "mock":
		*hType = MockHypervisor
		return nil
	default:
		return fmt.Errorf("Unknown hypervisor type %s", value)
	}
}

// String converts an hypervisor type to a string.
func (hType *HypervisorType) String() string {
	switch *hType {
	case QemuHypervisor:
		return string(QemuHypervisor)
	case FirecrackerHypervisor:
		return string(FirecrackerHypervisor)
	case MockHypervisor:
		return string(MockHypervisor)
	default:
		return ""
	}
}

// newHypervisor returns an hypervisor from and hypervisor type.
func newHypervisor(hType HypervisorType) (hypervisor, error) {
	switch hType {
	case QemuHypervisor:
		return &qemu{}, nil
	case FirecrackerHypervisor:
		return &firecracker{}, nil
	case MockHypervisor:
		return &mockHypervisor{}, nil
	default:
		return nil, fmt.Errorf("Unknown hypervisor type %s", hType)
	}
}

// Param is a key/value representation for hypervisor and kernel parameters.
type Param struct {
	Key   string
	Value string
}

// HypervisorConfig is the hypervisor configuration.
type HypervisorConfig struct {
	// NumVCPUs specifies default number of vCPUs for the VM.
	NumVCPUs uint32

	//DefaultMaxVCPUs specifies the maximum number of vCPUs for the VM.
	DefaultMaxVCPUs uint32

	// DefaultMem specifies default memory size in MiB for the VM.
	MemorySize uint32

	// DefaultBridges specifies default number of bridges for the VM.
	// Bridges can be used to hot plug devices
	DefaultBridges uint32

	// Msize9p is used as the msize for 9p shares
	Msize9p uint32

	// MemSlots specifies default memory slots the VM.
	MemSlots uint32

	// MemOffset specifies memory space for nvdimm device
	MemOffset uint32

	// VirtioFSCacheSize is the DAX cache size in MiB
	VirtioFSCacheSize uint32

	// KernelParams are additional guest kernel parameters.
	KernelParams []Param

	// HypervisorParams are additional hypervisor parameters.
	HypervisorParams []Param

	// KernelPath is the guest kernel host path.
	KernelPath string

	// ImagePath is the guest image host path.
	ImagePath string

	// InitrdPath is the guest initrd image host path.
	// ImagePath and InitrdPath cannot be set at the same time.
	InitrdPath string

	// FirmwarePath is the bios host path
	FirmwarePath string

	// MachineAccelerators are machine specific accelerators
	MachineAccelerators string

	// HypervisorPath is the hypervisor executable host path.
	HypervisorPath string

	// BlockDeviceDriver specifies the driver to be used for block device
	// either VirtioSCSI or VirtioBlock with the default driver being defaultBlockDriver
	BlockDeviceDriver string

	// HypervisorMachineType specifies the type of machine being
	// emulated.
	HypervisorMachineType string

	// MemoryPath is the memory file path of VM memory. Used when either BootToBeTemplate or
	// BootFromTemplate is true.
	MemoryPath string

	// DevicesStatePath is the VM device state file path. Used when either BootToBeTemplate or
	// BootFromTemplate is true.
	DevicesStatePath string

	// EntropySource is the path to a host source of
	// entropy (/dev/random, /dev/urandom or real hardware RNG device)
	EntropySource string

	// Shared file system type:
	//   - virtio-9p (default)
	//   - virtio-fs
	SharedFS string

	// VirtioFSDaemon is the virtio-fs vhost-user daemon path
	VirtioFSDaemon string

	// VirtioFSCache cache mode for fs version cache or "none"
	VirtioFSCache string

	// customAssets is a map of assets.
	// Each value in that map takes precedence over the configured assets.
	// For example, if there is a value for the "kernel" key in this map,
	// it will be used for the sandbox's kernel path instead of KernelPath.
	customAssets map[types.AssetType]*types.Asset

	// BlockDeviceCacheSet specifies cache-related options will be set to block devices or not.
	BlockDeviceCacheSet bool

	// BlockDeviceCacheDirect specifies cache-related options for block devices.
	// Denotes whether use of O_DIRECT (bypass the host page cache) is enabled.
	BlockDeviceCacheDirect bool

	// BlockDeviceCacheNoflush specifies cache-related options for block devices.
	// Denotes whether flush requests for the device are ignored.
	BlockDeviceCacheNoflush bool

	// DisableBlockDeviceUse disallows a block device from being used.
	DisableBlockDeviceUse bool

	// EnableIOThreads enables IO to be processed in a separate thread.
	// Supported currently for virtio-scsi driver.
	EnableIOThreads bool

	// Debug changes the default hypervisor and kernel parameters to
	// enable debug output where available.
	Debug bool

	// MemPrealloc specifies if the memory should be pre-allocated
	MemPrealloc bool

	// HugePages specifies if the memory should be pre-allocated from huge pages
	HugePages bool

	// File based memory backend root directory
	FileBackedMemRootDir string

	// Realtime Used to enable/disable realtime
	Realtime bool

	// Mlock is used to control memory locking when Realtime is enabled
	// Realtime=true and Mlock=false, allows for swapping out of VM memory
	// enabling higher density
	Mlock bool

	// DisableNestingChecks is used to override customizations performed
	// when running on top of another VMM.
	DisableNestingChecks bool

	// UseVSock use a vsock for agent communication
	UseVSock bool

	// HotplugVFIOOnRootBus is used to indicate if devices need to be hotplugged on the
	// root bus instead of a bridge.
	HotplugVFIOOnRootBus bool

	// BootToBeTemplate used to indicate if the VM is created to be a template VM
	BootToBeTemplate bool

	// BootFromTemplate used to indicate if the VM should be created from a template VM
	BootFromTemplate bool

	// DisableVhostNet is used to indicate if host supports vhost_net
	DisableVhostNet bool

	// GuestHookPath is the path within the VM that will be used for 'drop-in' hooks
	GuestHookPath string

	// VMid is the id of the VM that create the hypervisor if the VM is created by the factory.
	// VMid is "" if the hypervisor is not created by the factory.
	VMid string
}

// vcpu mapping from vcpu number to thread number
type vcpuThreadIDs struct {
	vcpus map[int]int
}

func (conf *HypervisorConfig) checkTemplateConfig() error {
	if conf.BootToBeTemplate && conf.BootFromTemplate {
		return fmt.Errorf("Cannot set both 'to be' and 'from' vm tempate")
	}

	if conf.BootToBeTemplate || conf.BootFromTemplate {
		if conf.MemoryPath == "" {
			return fmt.Errorf("Missing MemoryPath for vm template")
		}

		if conf.BootFromTemplate && conf.DevicesStatePath == "" {
			return fmt.Errorf("Missing DevicesStatePath to load from vm template")
		}
	}

	return nil
}

func (conf *HypervisorConfig) valid() error {
	if conf.KernelPath == "" {
		return fmt.Errorf("Missing kernel path")
	}

	if conf.ImagePath == "" && conf.InitrdPath == "" {
		return fmt.Errorf("Missing image and initrd path")
	}

	if err := conf.checkTemplateConfig(); err != nil {
		return err
	}

	if conf.NumVCPUs == 0 {
		conf.NumVCPUs = defaultVCPUs
	}

	if conf.MemorySize == 0 {
		conf.MemorySize = defaultMemSzMiB
	}

	if conf.DefaultBridges == 0 {
		conf.DefaultBridges = defaultBridges
	}

	if conf.BlockDeviceDriver == "" {
		conf.BlockDeviceDriver = defaultBlockDriver
	}

	if conf.DefaultMaxVCPUs == 0 {
		conf.DefaultMaxVCPUs = defaultMaxQemuVCPUs
	}

	if conf.Msize9p == 0 {
		conf.Msize9p = defaultMsize9p
	}

	return nil
}

// AddKernelParam allows the addition of new kernel parameters to an existing
// hypervisor configuration.
func (conf *HypervisorConfig) AddKernelParam(p Param) error {
	if p.Key == "" {
		return fmt.Errorf("Empty kernel parameter")
	}

	conf.KernelParams = append(conf.KernelParams, p)

	return nil
}

func (conf *HypervisorConfig) addCustomAsset(a *types.Asset) error {
	if a == nil || a.Path() == "" {
		// We did not get a custom asset, we will use the default one.
		return nil
	}

	if !a.Valid() {
		return fmt.Errorf("Invalid %s at %s", a.Type(), a.Path())
	}

	virtLog.Debugf("Using custom %v asset %s", a.Type(), a.Path())

	if conf.customAssets == nil {
		conf.customAssets = make(map[types.AssetType]*types.Asset)
	}

	conf.customAssets[a.Type()] = a

	return nil
}

func (conf *HypervisorConfig) assetPath(t types.AssetType) (string, error) {
	// Custom assets take precedence over the configured ones
	a, ok := conf.customAssets[t]
	if ok {
		return a.Path(), nil
	}

	// We could not find a custom asset for the given type, let's
	// fall back to the configured ones.
	switch t {
	case types.KernelAsset:
		return conf.KernelPath, nil
	case types.ImageAsset:
		return conf.ImagePath, nil
	case types.InitrdAsset:
		return conf.InitrdPath, nil
	case types.HypervisorAsset:
		return conf.HypervisorPath, nil
	case types.FirmwareAsset:
		return conf.FirmwarePath, nil
	default:
		return "", fmt.Errorf("Unknown asset type %v", t)
	}
}

func (conf *HypervisorConfig) isCustomAsset(t types.AssetType) bool {
	_, ok := conf.customAssets[t]
	return ok
}

// KernelAssetPath returns the guest kernel path
func (conf *HypervisorConfig) KernelAssetPath() (string, error) {
	return conf.assetPath(types.KernelAsset)
}

// CustomKernelAsset returns true if the kernel asset is a custom one, false otherwise.
func (conf *HypervisorConfig) CustomKernelAsset() bool {
	return conf.isCustomAsset(types.KernelAsset)
}

// ImageAssetPath returns the guest image path
func (conf *HypervisorConfig) ImageAssetPath() (string, error) {
	return conf.assetPath(types.ImageAsset)
}

// CustomImageAsset returns true if the image asset is a custom one, false otherwise.
func (conf *HypervisorConfig) CustomImageAsset() bool {
	return conf.isCustomAsset(types.ImageAsset)
}

// InitrdAssetPath returns the guest initrd path
func (conf *HypervisorConfig) InitrdAssetPath() (string, error) {
	return conf.assetPath(types.InitrdAsset)
}

// CustomInitrdAsset returns true if the initrd asset is a custom one, false otherwise.
func (conf *HypervisorConfig) CustomInitrdAsset() bool {
	return conf.isCustomAsset(types.InitrdAsset)
}

// HypervisorAssetPath returns the VM hypervisor path
func (conf *HypervisorConfig) HypervisorAssetPath() (string, error) {
	return conf.assetPath(types.HypervisorAsset)
}

// CustomHypervisorAsset returns true if the hypervisor asset is a custom one, false otherwise.
func (conf *HypervisorConfig) CustomHypervisorAsset() bool {
	return conf.isCustomAsset(types.HypervisorAsset)
}

// FirmwareAssetPath returns the guest firmware path
func (conf *HypervisorConfig) FirmwareAssetPath() (string, error) {
	return conf.assetPath(types.FirmwareAsset)
}

// CustomFirmwareAsset returns true if the firmware asset is a custom one, false otherwise.
func (conf *HypervisorConfig) CustomFirmwareAsset() bool {
	return conf.isCustomAsset(types.FirmwareAsset)
}

func appendParam(params []Param, parameter string, value string) []Param {
	return append(params, Param{parameter, value})
}

// SerializeParams converts []Param to []string
func SerializeParams(params []Param, delim string) []string {
	var parameters []string

	for _, p := range params {
		if p.Key == "" && p.Value == "" {
			continue
		} else if p.Key == "" {
			parameters = append(parameters, fmt.Sprint(p.Value))
		} else if p.Value == "" {
			parameters = append(parameters, fmt.Sprint(p.Key))
		} else if delim == "" {
			parameters = append(parameters, fmt.Sprint(p.Key))
			parameters = append(parameters, fmt.Sprint(p.Value))
		} else {
			parameters = append(parameters, fmt.Sprintf("%s%s%s", p.Key, delim, p.Value))
		}
	}

	return parameters
}

// DeserializeParams converts []string to []Param
func DeserializeParams(parameters []string) []Param {
	var params []Param

	for _, param := range parameters {
		if param == "" {
			continue
		}
		p := strings.SplitN(param, "=", 2)
		if len(p) == 2 {
			params = append(params, Param{Key: p[0], Value: p[1]})
		} else {
			params = append(params, Param{Key: p[0], Value: ""})
		}
	}

	return params
}

func getHostMemorySizeKb(memInfoPath string) (uint64, error) {
	f, err := os.Open(memInfoPath)
	if err != nil {
		return 0, err
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		// Expected format: ["MemTotal:", "1234", "kB"]
		parts := strings.Fields(scanner.Text())

		// Sanity checks: Skip malformed entries.
		if len(parts) < 3 || parts[0] != "MemTotal:" || parts[2] != "kB" {
			continue
		}

		sizeKb, err := strconv.ParseUint(parts[1], 0, 64)
		if err != nil {
			continue
		}

		return sizeKb, nil
	}

	// Handle errors that may have occurred during the reading of the file.
	if err := scanner.Err(); err != nil {
		return 0, err
	}

	return 0, fmt.Errorf("unable get MemTotal from %s", memInfoPath)
}

// RunningOnVMM checks if the system is running inside a VM.
func RunningOnVMM(cpuInfoPath string) (bool, error) {
	if runtime.GOARCH == "arm64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x" {
		virtLog.Info("Unable to know if the system is running inside a VM")
		return false, nil
	}

	flagsField := "flags"

	f, err := os.Open(cpuInfoPath)
	if err != nil {
		return false, err
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		// Expected format: ["flags", ":", ...] or ["flags:", ...]
		fields := strings.Fields(scanner.Text())
		if len(fields) < 2 {
			continue
		}

		if !strings.HasPrefix(fields[0], flagsField) {
			continue
		}

		for _, field := range fields[1:] {
			if field == "hypervisor" {
				return true, nil
			}
		}

		// As long as we have been able to analyze the fields from
		// "flags", there is no reason to check what comes next from
		// /proc/cpuinfo, because we already know we are not running
		// on a VMM.
		return false, nil
	}

	if err := scanner.Err(); err != nil {
		return false, err
	}

	return false, fmt.Errorf("Couldn't find %q from %q output", flagsField, cpuInfoPath)
}

// hypervisor is the virtcontainers hypervisor interface.
// The default hypervisor implementation is Qemu.
type hypervisor interface {
	createSandbox(ctx context.Context, id string, hypervisorConfig *HypervisorConfig, store *store.VCStore) error
	startSandbox(timeout int) error
	stopSandbox() error
	pauseSandbox() error
	saveSandbox() error
	resumeSandbox() error
	addDevice(devInfo interface{}, devType deviceType) error
	hotplugAddDevice(devInfo interface{}, devType deviceType) (interface{}, error)
	hotplugRemoveDevice(devInfo interface{}, devType deviceType) (interface{}, error)
	resizeMemory(memMB uint32, memoryBlockSizeMB uint32, probe bool) (uint32, memoryDevice, error)
	resizeVCPUs(vcpus uint32) (uint32, uint32, error)
	getSandboxConsole(sandboxID string) (string, error)
	disconnect()
	capabilities() types.Capabilities
	hypervisorConfig() HypervisorConfig
	getThreadIDs() (vcpuThreadIDs, error)
	cleanup() error
	pid() int
	fromGrpc(ctx context.Context, hypervisorConfig *HypervisorConfig, store *store.VCStore, j []byte) error
	toGrpc() ([]byte, error)
}